#!/usr/bin/env python3
# -*- coding: utf-8-*-
import numpy as np
if __name__ == '__main__':
    n = int(input())
    w = np.array(list(map(int, input().split(" "))))
    s = sum(w)
    if s % 2 == 1:
        print("impossible")
        exit()
    s //= 2
    t = np.zeros((n+1, s+1))
    t[0,0] = 1
    for i in range(n):
        for j in range(s+1):
            if t[i, j] == 1:
                t[i+1, j] = 1
                if j + w[i] <= s:
                    t[i+1, j+w[i]] = 1
    if t[n,s] == 1:
        print("possible")
    else:
        print("impossible")